HELP!! Taking 2 inputs (L+R) and having 3 outputs (L, R, SUM)

[JP19]

Hi, As you might have guessed by my question I don't really know what I'm doing (but am blundering on with building some pedals anyway) and I was hoping someone could help me! I'm sure this is pretty basic.


I'm trying to stereo link 2 compressor pedals so I can mess with them on drum loops etc.


I had them working as 2 separate (identical) compressor circuits but I wanted to stereo link them.


So next I managed to make it work by having signal present at the left side control gain reduction for both sides, but this isn't great because if I get a loud spike only on the right side, I get no compression with this arrangement.


Ideally I would like to take a sum of the left and right signals, which i can send to the detection circuit, but leaving the left and right signals unaffected to pass on into the compressor.

What would be the easiest way to do this?

I should mention that the left and right signals are already buffered at the point I want to take the 'tap' from.

Thanks!

[PRR]

Actually you may not want "sum", you may want "MAX of L or R".

There are SOOO many "compressors". Most have part of this stuff inside. Can you tell us what compressors you have?

[JP19]

Ah ok maybe this is more complicated than I thought!

It's this compressor I have built 2 of: http://www.thatcorp.com/pedals/4315%20Guitar%20Compressor%20with%20Variable%20Attack%20and%20Release%20r0A.1.pdf

I've currently disconnected all the circuitry from the right channel (from c1 all the way to the VCA) and I have tied pin 12 of the left and right VCAs together. This is working for stereo compression but as I said obviously doesn't get triggered by the right side.

Is there an easy way to make this work properly?

If not I can totally live with what I've got!

Thanks

[PRR]

The THAT chips are very smart, too smart for my brain.

What happens, dual-mono, if the two RMS cells' CT pins are strapped together? In a rectifier sidechain that can compute MAX(L||R) which is good.

[JP19]

Hmm I have no idea... I'll give that a go and report back!

[JP19]

Thanks so much PRR! I'm not going to pretend I understand why that works, but it does!